The field of pressurised hydrogen technology including a hydrogen transfer membrane is used in hydrogen fed power systems. Due to the fact that hydrogen fed power systems are normally operated with hydrogen that originates from a hydrogen container and the low volumetric energy density of gaseous hydrogen, hydrogen is normally compressed and stored at high pressures, typically at a value of about 20 MPa, of about 35 MPa or even of about 70 MPa and higher. Alternatively, hydrogen can be liquefied. Both compression and liquefaction of hydrogen require substantial energy. The energy for compression or liquefaction reduces the total energy efficiency of a hydrogen fed power systems (in automotive applications also referred to as; “well-to-wheel efficiency”). Recovery of this compression energy or liquefaction energy has been attempted in several ways. Hydrogen circulation can be accomplished using ejectors. These ejectors partially use the kinetic energy of a high pressure, high speed hydrogen gas stream. Such ejectors save energy that would otherwise be consumed by mechanical circulation pumps, however only a fraction of the invested compression energy is recovered this way. Alternatively a piston pump, a turbine or mechanical membrane pump can be used as de-compressor (expander) for the high pressure hydrogen. In this way a substantial part of the energy can be recovered. However, mechanical de-compressors like piston or reverse membrane pumps are noisy, expensive, heavy, bulky and require regular maintenance, and are therefore not very attractive.
It is an object of embodiments of the invention to improve the overall energy efficiency of hydrogen fed power systems preventing the above mentioned disadvantages of the prior art systems.